We all know that homeownership is considered the cornerstone of the American dream. But many of us take that dream for granted. I was reminded of this when I attended the dedication and blessing of a home with Habitat for Humanity in Chester, Pennsylvania outside of Philadelphia.

As a corporate sponsor of what we have come to refer to as the “CertainTeed House” because of the many CertainTeed products incorporated into the building envelop of this two-family house, I participated in the dedication and blessing of the house. The family, a single mother with two daughters who will occupy half of the house, seemed simultaneously overwhelmed and excited.

The group of family, friends, sponsors and supporters clustered into what would soon be the family’s living room as the Reverend began the dedication and blessing. The group traveled from room to room with the family carrying a candle as each area was given a special blessing – from the kitchen where nourishment is prepared to the dining room where bread is broken and shared to the bedrooms where sleeping safe and secure is desired. Once the blessing was completed, the keys were presented to the family marking the final transformation of this building from simply a house into a home.

It was beautiful!

But there was an added sense of pride that I felt standing in this completed house that would be the dream home for this family. Over ten weeks during the building of this house approximately 80 of my co-workers volunteered time on the site to help with the build. The opportunity to gain hands-on experience with CertainTeed roofing shingles, housewrap, vinyl siding and railing, insulation and gypsum products was as valuable as the satisfaction of giving back to the community in this very special way. In some cases it brought employees together whose paths would not cross at work and in other cases departmental teams used this as a teambuilding exercise.

In the end, it was a learning experience for all and a lesson in community that has no equal.

Building wraps are now required behind all cladding by the International Residential Code. If you are building over a wood frame you must use a secondary water resistive barrier (WRB). Recent research has shown that as much as 10 percent of the wind driven rain is getting past the cladding onto the back-up layer. Intruding water must be redirected toward the exterior and not allowed to accumulate within the wall assemblies. This is the function of the water resistive barrier.

Install-ability – Is it tough enough to withstand exposure to the elements over a period of time? Building wraps need to hold up to winds, not rip over staples and stay in place once installed.

Balanced set of physical properties – Select a material that is somewhat vapor open but not too vapor open. There is a relatively healthy balance for a variety of cladding assemblies based on what the appropriate permeance is at that layer. Much of the computer modeling that I have done over the years indicates a good general number for the permeance is between 10 – 20 U.S. perms for most U.S. climates.

Always install in accordance with the manufacturer’s recommendations – This becomes your principle means of defense for moisture. Moisture intrusion must stop at this line.

Building wrap needs to be installed in a shingle-like manner, so that it sheds water to the outside. It should also be installed in coordination with flashings and other accessories to ensure that any moisture that does intrude the assembly gets stopped at this layer. It must then be redirected to the exterior and not become entrapped within the wall somewhere else.

Common sense is something that our fathers and grandfathers did far better than we do today. Today the tendency is to rely on the silver bullet of technology to help pull us out of the fire. The fact is, if you take these materials and install them with a great deal of common sense and construction knowledge, as older tradesmen did, then they work really well. In the best circumstances, the marriage of good technology and practical knowledge coincide and we construct durable and sustainable buildings. The correct application of a proper water resistive barrier is an example of such an installation. It’s not rocket science, it’s good building science.

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

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